﻿#include <stdio.h>
main( )
{	 	 	   	    
	int  up=9, low=0, mid,found=0, find;
	int  a[10]={1, 5, 6, 9, 11, 17, 25, 34, 38, 41};
	scanf("%d", &find);
	printf("\n");
	while (up>=low  &&  !found)
	{	 	 	   	    
		mid=(up+low)/2;
		if(a[mid]==find)
		{	 	 	   	    
			found=1;  
			break;
		}
		else  if(a[mid]>find)
				up=mid-1;
		      else    
				low=mid+1;
	}
	if(found) 
		printf("found number is %dth.\n",mid);
	else  
		printf("no  found.\n");
}	 	 	   	    